Color picture tube device

ABSTRACT

A color picture tube device having a &#39;&#39;&#39;&#39;blue&#39;&#39;&#39;&#39; convergence pole piece and a pair of &#39;&#39;&#39;&#39;red&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;green&#39;&#39;&#39;&#39; convergence pole pieces provided therein, wherein the &#39;&#39;&#39;&#39;red&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;green&#39;&#39;&#39;&#39; convergence pole pieces are disposed in opposing relationship to each other at an angle smaller than 120*C, electrodes are provided such that each is in parallel with each of the pair of pole pieces respectively, &#39;&#39;&#39;&#39;red&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;green&#39;&#39;&#39;&#39; beams being made to pass between the electrodes and the pair of pole pieces so that three, &#39;&#39;&#39;&#39;red&#39;&#39;&#39;&#39;, &#39;&#39;&#39;&#39;blue&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;green&#39;&#39;&#39;&#39;, beams may be moved on the screen with an angle of 120* being maintained therebetween.

United States Patent Egawa et al.

[ 5] Oct. 24, 1972 [54] COLOR PICTURE TUBE DEVICE [72] Inventors: Susumu Egawa, Osaka; Shigeya Ashizaki, Takatsuki-shi; Katsumi Shimizu, Ibaragi-shi; Tosihiko Miyati, Osaka, all of Japan [73] Assignee: Matsushita Electric Industrial Co., Ltd., Osaka, Japan [22] Filed: Jan. 19, 1970 [21] Appl. No.: 3,899

[52] US. Cl. ..315/13 C [51] Int. Cl ..H0lj 29/50 [58] Field of Search ..3l5/l3 C; 313/76, 77

[56] References Cited UNITED STATES PATENTS 3,375,389 3/1968 Hughes ..313/77 3,461,341 8/1969 Egawa ..3l5/13 C Primary Examiner-Carl D. Quarforth Assistant Examiner-D. M. Potenza Att0rneyStevens, Davis, Miller & Mosher ABSTRACT A color picture tube device having a blue convergence pole piece and a pair of red and green convergence pole pieces provided therein, wherein the red and green convergence pole pieces are disposed in opposing relationship to each other at an angle smaller than 120C, electrodes are provided such that each is in parallel with each of the pair of pole pieces respectively, red and green beams being made to pass between the electrodes and the pair of pole pieces so that three, red, blue and green, beams may be moved on the screen with an angle of 120 being maintained therebetween.

5 Claims, 8 Drawing Figures P'A'TE'NTEDnm 24 um sum 1 or 3 PRIOR ART PRIOR ART H! m 4 W PU.

K Jim/2a;

INVENTORS ATTORNEYS PKTENTED 1973 3 700,954

sum 2 OF 3 PRIOR ART PRIOR ART COLOR PICTURE TUBE DEVICE This invention relates to a color picture tube device.

In the conventional so-called two-pole convergence device of the delta gun type (electron guns are positioned at the vertices of a triangle), the convergence yoke attached to the picture tube 5 is constructed in the form of a double-pole, without any modifications to convergence pole pieces 6, 6' and 6" and portions related thereto (referred to as the top unit) provided in the picture tube, as shown in FIG. 1. Such a device is disclosed in U.S. Pat. Nos. 3,454,807 and 3,461,341, wherein static red and green convergence is simultaneously effected by means of a single magnet 2 and a dynamic one is also simultaneously effected by means of a single magnet 4. Numerals 1 and 3 represent static and dynamic blue convergence magnets respectively, and 7 a shield plate.

The magnetic field distribution occurring in the foregoing system is as shown in FIG. 2. That is, the magnetic fields in those portions (indicated by R G B of the top unit through which electron beams pass turn out to be approximately perpendicular so that forces imparted to the beams R and G or motions thereof are directed as shown by the arrow marks, and consequently these beams tend to be deviated from their desired directions (indicated by A and A respectively in FIG. 2). The extent to which the dots are scattered on the screen prior to the dynamic convergence (misconvergence) in the periphery of the screen is as shown by R and G in FIG. 3 for example. This has no relation to blue, and therefore the description related thereto will be omitted. FIG. 3a shows a desired form of convergence, wherein vectors r and g indicate AMP components respectively, most the misconvergence is corrected by adjusting said components, and the remainder d is corrected by DIFF (differential) components r and g P indicates a position where R and G dots are in registry with each other. FIG. 3b corresponds to the magnetic field distribution shown in FIG. 2, wherein the amount of the remainder d corrected with respect to the AMP components r, and g, remains unchanged, but the required amount of differential correction r and g is remarkably increased. The angle is smaller than 30. In this case, the registry point P is greatly deviated from the horizontal center point between R and G, thus resulting in increased misconvergence with blue. Due to the electrode construction and/or configuration of external electromagnet (convergence yoke core), vertical misconvergence shown in FIG. 30 (misconvergence which is to be differentially corrected) becomes impossible when the moving directions of the beams R and G approach the horizontal direction.

The present invention is intended to eliminate the aforementioned drawbacks.

It is an object of the present invention to improve the pole pieces of a delta gun type picture tube so as to make it possible to achieve satisfactory differential correction.

Another object of the present invention is to provide an electrode structure which is conveniently adapted to achieve the foregoing object.

Other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a plan view, partly in section, showing the aforementioned conventional picture tube for color television receivers;

FIG. 2 is a view showing the magnetic field distribution occurring in said picture tube;

FIGS. 3a, 3b and 3c are vector views useful for explaining the operation of FIG. 2, respectively;

FIG. 4 is a view showing the electrode structure of the color picture tube and magnetic field distribution occurring therein, according to an embodiment of the present invention;

FIG. 5 is a view showing the electrode structure according to a second embodiment of the present invention; and

FIG. 6 is a view showing characteristics useful for explaining the picture tube shown in FIG. 4.

With reference to FIG. 4, description will first be made of an example wherein the conventional top unit is modified as little as possible.

The gist of the present invention resides in the formation of pole pieces exclusively adapted for two-pole convergence which are designed so that the magnetic reluctance of the magnetic paths for convergence is minimized by utilizing the fact that none of the magnetic fields passing through the intermediate portion R between parallel electrodes K and K and the intermediate portion G between parallel electrodes L and L respectively has substantially any component perpendicular to the electrodes K and K. The concrete construction will now be described. Numeral 8 represents a blue dynamic convergence magnet, 9 red and green dynamic convergence magnets, 10 a picture tube, and 11 a blue pole piece. These elements are similar in construction to those of the conventional device shown in FIG. 1.

In accordance with the present invention, pair of red green pole pieces 12 is substituted for the two pole pieces 6 and 6 shown in FIG. 1, and the pole pieces K and L of the pair of pole pieces 12 are disposed in opposing relationship to each other with an angle of a maintained therebetween. Further, the Y- shaped shield plate shown in FIG. 1 is constructed in the form of a V-shaped shield plate 13 so as to contain the blue pole piece therein. This shield plate 13 serves as a magnetic guide. Mounted on the shield plate 13 are the electrodes K and L disposed in opposing relationship to the pole pieces K and L of the pair of pole pieces 12 so that beams G and R are made to pass between the electrode the pole piece L and L and between K and K respectively. It has been experimentally confirmed that the greater the distance 1 between the electrode the pole pieces K and K and between L and L, the more the magnetic fields passing through the intermediate portions between these electrodes and pair of pole pieces are deviated from the directions perpendicular to the electrode plates. Thus, although in the prior art, the angle between the R and G electrode plates has been selected to be the design is made so that the directions in which the electron beams R G in FIG. 4) are in registry with the desired directions A A respectively in accordance with the present invention. The angle between A and A is 120. The relationship of the angle a between the R and G pole pieces K and L to the angle [3 between the electron beam moving directions as horizontally viewed becomes as shown in FIG. 6. From this Figure,

a is in the neighborhood of 30 to make B= 30, where 1 represents the most desirable electrode spacing.

It is desired that the electrode spacing I, be selected as small as possible from the standpoint of convergence sensitivity but as great as possible from the standpoint of tolerance for the electron beam thickness. Generally, this spacing is selected to be about mm. As will be seen from FIG. 6, a may be selected to be great for the case where the spacing is small while it may be selected to be small for the case where the spacing is great. Assuming that the configuration can be arbitrarily selected completely independently of the conventional top unit, another embodiment such as shown in FIG. 5 will become possible wherein magnetic lines of force pass substantially at right angles with respect to the desired beam moving directions A and A Provision of a magnetic shield plate between B and R, G is effective to reduce mutual interference between B and R, G. Parts of FIG. 5 corresponding to those of FIG. 4 are indicated by like numerals. The shield plate 13 is formed by a single flat plate, and electrodes L and K are integrally formed in a substantially U-shaped section.

In both of the embodiments shown in FIGS. 4 and 5, cores 8 and 9 are provided in opposing relationship to the pole piece 11 and the pair of pole pieces 12 respectively, so that static and dynamic convergence operations can be performed as in the conventional devices of this type. Advantageously, differential control (correction for longitudinal deviations of R, G) can be effectively achieved, as compared with two-pole convergence, in which a picture tube having three pole pieces is used as it is. The aforementioned core 9 is U-shaped and has dynamic convergence windings provided on the opposite legs thereof. These windings are connected in series with each other through which a parabolic current is made to flow. A differential current may be supplied to the connection point between the windings. Alternatively, a winding may be provided on the core in such a manner as to cover both of the legs thereof, and a current may be made to flow therethrough. Also provided on the opposite legs of the aforementioned core 8 are dynamic convergence windings connected in series with each other through which a parabolic current is made to flow. Furthermore, rotatable and upwardly-downwardly movable magnets which are two-pole-magnetized are provided on the cores 8 and 9 thereby to effect static convergence control. All the foregoing elements are provided to apply magnetic fields for convergence control to the pole piece 11 and the pair of pole pieces 12.

What is claimed is:

l. A convergence device for use with a picture tube having an electron gun of the delta type comprising a first convergence pole piece for controlling a first electron beam,

second and third convergence pole pieces for controlling second and third electron beams respectively, said second and third convergence pole pieces being positioned at a predetermined angle with respect to each other,

first and second electrodes positioned in a spaced, substantially parallel relationship with said second and third pole pieces respectively, said second electron beam bein inte psosed between said second pole piece an said t electrode and said third electron beam being interposed between said third pole piece and said second electrode, said convergence pole pieces and said electrodes being mounted within said picture tube, and

means located external to said picture tube of providing convergence controlling magnetic fields to said first, second and third pole pieces in opposing relationship to said pole pieces, the predetermined angle between said second and third convergence pole pieces being determined so that the three electron beams can be moved with an angle of being maintained therebetween.

2. A convergence device as defined by claim 1 which further comprises a shield plate provided within said tube between said first pole piece and said second and third pole pieces to prevent interference between said first pole piece and said second and third pole pieces.

3. A convergence device as defined by claim 2 wherein said shield plate is configured in a V-shape, and said first and second electrodes are attached to said V-shaped shield plate.

4. A convergence device as defined by claim 2 wherein said shield plate is formed by a single flat plate, and said first and second electrodes are formed in tegrally with each other.

5. A convergence device for use with a picture tube having an electron gun of the delta type comprising a first convergence pole piece for controlling a first electron beam,

second and third convergence pole pieces for controlling second and third electron beams respectively, said second and third convergence pole pieces being positioned at a predetermined angle with respect to each other, and

first and second electrodes positioned in a spaced,

substantially parallel relationship with said second and third pole pieces respectively, said second electron beam being interposed between said second pole piece and said first electrode and said third electron beam being interposed between said third pole piece and said second electrode, said convergence pole pieces and said electrodes being mounted within said picture tube, the predetermined angle between said second and third convergence pole pieces being determined so that the three electron beams can be moved with an angle of 120 being maintained therebetween. 

1. A convergence device for use with a picture tube having an electron gun of the delta type comprising a first convergence pole piece for controlling a first electron beam, second and third convergence pole pieces for controlling second and third electron beams respectively, said second and third convergence pole pieces being positioned at a predetermined angle with respect to each other, first and second electrodes positioned in a spaced, substantially parallel relationship with said second and third pole pieces respectively, said second electron beam being interposed between said second pole piece and said first electrode and said third electron beam being interposed between said third pole piece and said second electrode, said convergence pole pieces and said electrodes being mounted within said picture tube, and means located external to said picture tube of providing convergence controlling magnetic fields to said first, second and third pole pieces in opposing relationship to said pole pieces, the predetermined angle between said second and third convergence pole pieces being determined so that the three electron beams can be moved with an angle of 120* being maintained therebetween.
 2. A convergence device as defined by claim 1 which further comprises a shield plate provided within said tube between said first pole piece and said second and third pole pieces to prevent interference between said first pole piece and said second and third pole pieces.
 3. A convergence device as defined by claim 2 wherein said shield plate is configured in a V-shape, and said first and second electrodes are attached to said V-shaped shield plate.
 4. A convergence device as defined by claim 2 wherein said shield plate is formed by a single flat plate, and said first and second electrodes are formed integrally with each other.
 5. A convergence device for use with a picture tube having an electron gun of the delta type comprising a first convergence pole piece for controlling a first electron beam, second and third convergence pole pieces for controlling second and third electron beams respectively, said second and third convergence pole pieces being positioned at a predetermined angle with respect to each other, and first and second electrodes positioned in a spaced, substantially parallel relationship with said second and third pole pieces respectively, said second electron beam being interposed between said second pole piece and said first electrode and said third electron beam being interposed between said third pole piece and said second electrode, said convergence pole pieces and said electrodes being mounted within said picture tube, the predetermined angle between said second and third convergence pole pieces being determined so that the three electron beams can be moved with an angle of 120* being maintained therebetween. 